Vibration actuator and electronic device
This vibration actuator comprises a fixed body including a coil, a movable body including a magnet, and an elastic support part that supports the movable body so as to be freely moveable with respect to the fixed body. The elastic support part has an outer circumferential part fixed to the fixed body, an inner circumferential part disposed inside in the radial direction of the outer circumferential part and fixed to the movable body, and a deforming arm part disposed between the outer circumferential part and the inner circumferential part and coupling the outer circumferential part and the inner circumferential part, the deforming arm part being elastically deformable. An attenuation part is provided across the outer circumferential part and a portion of the deforming arm part on an outer circumferential part side thereof, the attenuation part attenuating vibrations in the elastic support part when the movable body moves.
1. A vibration actuator, comprising:
a fixing body including a coil;
a movable body including a magnet that is disposed inside the coil in a radial direction of the coil to be relatively movable in a vibration direction orthogonal to the radial direction of the coil; and
an elastic supporting part that supports the movable body such that the movable body is freely movable with respect to the fixing body, wherein
cooperation between the coil supplied with electricity and the magnet causes the movable body to vibrate with respect to the fixing body,
the elastic supporting part includes:
an outer circumferential portion fixed to the fixing body,
an inner circumferential portion disposed inside the outer circumferential portion in the radial direction and fixed to the movable body, and
a deformation arm portion disposed between the outer circumferential portion and the inner circumferential portion, the deformation arm portion being configured to couple together the outer circumferential portion and the inner circumferential portion, the deformation arm portion being elastically deformable in the vibration direction,
a damping part for damping a vibration of the elastic supporting part during movement of the movable body is disposed across the outer circumferential portion and an outermost portion of the deformation arm portion on the outer circumferential portion side, the outermost portion extending along the outer circumferential portion to form a curved gap extending in a curved shape between the outer circumferential portion and the outermost portion, such that the damping part bridges over a middle of the curved gap, and
a distance of the gap where the damping part is disposed is greater than twice a thickness dimension of the elastic supporting part and is less than or equal to six times the thickness dimension of the elastic supporting part.
2. The vibration actuator according to claim 1 , wherein:
the elastic supporting part is a spiral leaf spring, and
the deformation arm portion is disposed to extend along a circumferential direction, with a gap being interposed between the deformation arm portion and the outer circumferential portion in the radial direction with respect to the outer circumferential portion, the deformation arm portion being joined at one end portion to the outer circumferential portion and being joined at another end portion to the inner circumferential portion.
3. The vibration actuator according to claim 2 , wherein:
the deformation arm portion extends to intersect an imaginary line at a plurality of positions on the imaginary line, the imaginary line extending along the radial direction, and
the outermost portion of the deformation arm portion on the outer circumferential portion side is at a position of the plurality of positions which is on an outermost circumferential side.
4. The vibration actuator according to claim 3 , wherein:
the damping part includes:
an interposition portion that is disposed in the gap between the outer circumferential portion and the outermost portion of the deformation arm portion on the outer circumferential portion side, and that is joined to side surfaces of the outer circumferential portion and the outermost portion of the deformation arm portion on the outer circumferential portion side, the side surfaces facing each other in the radial direction, and
a protruding portion integrally formed with the interposition portion and protruding from the interposition portion in a thickness direction of the elastic supporting part, and
the protruding portion extends linearly to intersect the imaginary line and to cover the gap extending in a curved shape.
5. The vibration actuator according to claim 2 , wherein
the damping part includes an interposition portion disposed in the gap and joined to side surfaces of the outer circumferential portion and the deformation arm portion, the side surfaces facing each other in the radial direction.
6. The vibration actuator according to claim 5 , wherein:
the damping part includes a protruding portion integrally formed with the interposition portion and protruding from the interposition portion in a thickness direction of the elastic supporting part, and
a protruding dimension of the protruding portion from the interposition portion is larger than a thickness dimension of the elastic supporting part.
7. The vibration actuator according to claim 1 , wherein
a distance between a side surface of the outer circumferential portion and a side surface of the deformation arm portion that form a gap is greater than twice a thickness dimension of the elastic supporting part and is less than or equal to six times the thickness dimension of the elastic supporting part.
8. The vibration actuator according to claim 1 , wherein
the damping part is joined to at least one surface of front and back surfaces of the outer circumferential portion and the deformation arm portion, the front and back surfaces being separate from each other in a thickness direction of the elastic supporting part.
9. The vibration actuator according to claim 1 , wherein:
the fixing body includes a cylindrical coil holding part for holding the coil, and a case for accommodating the cylindrical coil holding part, and
the case includes, in an outer circumferential surface, a flat surface portion extending parallel to the vibration direction.
10. The vibration actuator according to claim 9 , wherein
a coil connection part is disposed at the flat surface portion.
11. The vibration actuator according to claim 9 , wherein
the case includes, in the outer circumferential surface, another flat surface portion extending parallel to the flat surface portion.
12. The vibration actuator according to claim 9 , wherein:
at a position corresponding to the flat surface portion, an inner circumferential surface of the cylindrical coil holding part and an outer circumferential surface of the magnet respectively include an inner circumferential flat surface portion and an outer circumferential flat surface portion facing each other, and
the outer circumferential flat surface portion is narrower than the inner circumferential flat surface portion in a direction perpendicular to the vibration direction.
13. The vibration actuator according to claim 9 , wherein:
an outer shape of the cylindrical coil holding part as seen in the vibration direction is circular, and
the cylindrical coil holding part as seen in the vibration direction is disposed eccentrically with respect to an outer-shape center of the case or an outer-diameter arc center of the case.
14. The vibration actuator according to claim 13 , wherein
a coil connection part is disposed on an outer-shape side of the case, the outer-shape side being on a side where a center of the cylindrical coil holding part is located with respect to the outer-shape center of the case of the cylindrical coil holding part.
15. The vibration actuator according to claim 13 , wherein
a coil connection part is disposed on the flat surface portion side formed in the outer circumferential surface of the case of the cylindrical coil holding part.
16. An electronic device in which
a vibration actuator according to claim 1 is mounted.